Regenerative Medicine Program (RMP) Program Highlights

Overview: Therapeutic Challenge Awardee Dr. Kapil Bharti of the National Eye Institute (NEI) and his research team have made major strides towards developing an inducible pluripotent stem cell (iPSC)-based therapy to treat age-related macular degeneration (AMD), a common cause of blindness. In AMD patients, Retinal Pigment Epithelium (RPE) cells – responsible for nourishing and supporting the retinal photoreceptor (light-sensitive) – become damaged and lose function. Replacement of damaged RPE cells with functional iPSC-derived RPE cells is a viable treatment believed to restore or improve vision. iPSCs are stem cells that have been reprogramed from adult cells and can develop into any cell type in the body. For clinical applications, iPSCs are to be manufactured using strict guidelines called current good manufacturing practice (cGMP) to ensure quality and clinical compatibility standards of cells. Dr. Bharti’s team has developed a streamlined manufacturing process to generate transplant-ready clinical-grade RPE cells from iPSCs. His team is currently working to complete the pre-clinical animal toxicity, efficacy, and transplantation device compatibility studies in preparation for submitting a phase I Investigational New Drug (IND) application with the U.S. Food and Drug Administration in late 2017 or early 2018. Learn more about Dr. Bharti’s research at NEI.

Project highlights: Over the past three years, Dr. Bharti’s team has overcome many challenges in bringing an iPSC-based therapy for AMD much closer to the clinic. Notable successes include (click link to expand and hide descriptive text):

Generating functional RPE cells from iPSCs is a two-step procedure: first isolate CD34+ cells from patient’s blood and reprogram them into iPSCs and then differentiate the iPSC to RPE cells by culturing them in rigidly defined cocktails of signaling molecules. This entire manufacturing process takes around 24 weeks. In addition, RPE cells within the eye are a polarized monolayer, meaning that the cell layer is only one-cell thick and that the bottom of the cells contain different surface proteins and perform different functions than the top of the cells. Ensuring that the iPSC-derived RPE cells develop the correct polarity is crucial if they are to function normally after transplantation.

In order to transplant iPSC-derived RPE cells into the eye, a specially designed biodegradable scaffold was developed that supports cell polarity, allows nutrient transfer, and has sufficient physical strength to support transplantation (see image below). Optimizing the scaffold was more difficult than anticipated and took close to two years to develop.

cGMP is a set of stringent regulations enforced by the FDA to ensure that drugs and biologics meet quality and safety standards required for clinical use. To comply with cGMP, Dr. Bharti’s team needs to ensure that every step of the manufacturing process – scaffold development and sterilization, CD43+ cell isolation and reprogramming to iPSCs, differentiation of iPSCs to RPEs, and cell shipment from the lab to the clinic – is performed under cGMP guidelines.

Preclinical studies assessing tumorigenicity of the implant, systemic and local toxicity, and efficacy are underway in rats and pigs. Preliminary studies show that transplanting a human clinical dose (8mm2 scaffold with a monolayer of 100,000 iPSC-derived RPE cells) into the eye of a pig following laser injury – to damage the RPE cells and simulate AMD-like damage – rescues the retinal photoreceptor (light-sensitive) cells. Dr. Bharti and his team are on track to file and IND with the FDA in late 2017 or early 2018.

This is a scanning electron microscope image of an RPE monolayer growing on top of a biodegradable scaffold (blue, left side of image). The polarity of the RPE cells is clearly visible (brown, bottom of cells in middle of image; green, top of cells on right side of image).

Current good manufacturing practices induced pluripotent stem cell line now available to enable development of new therapies and accelerate early-stage clinical research

Induced pluripotent stem cells (iPSCs) represent a powerful new avenue for potentially treating ailments ranging from Alzheimer's disease to spinal cord injury. Significant progress with stem cell therapy in mice is already underway; for instance, researchers have reversed diabetic conditions in mice using iPSC-generated insulin-producing beta-cells. Translating these studies into humans is the next challenge. The RMP supported, through a contract with Lonza Walkersville Inc., the development of a current good manufacturing practice (cGMP) clinical-grade iPSC line from human umbilical cord blood CD34+ cells. cGMP is a set of stringent regulations enforced by the US Food and Drug Administration that ensures each batch of cells produced will meet quality and safety standards required for potential clinical use. These cells were fully characterized for safety, sterility, plasmid clearance, endotoxin levels, karyotype and many other factors and are described in two publications by Behnam Baghbaderani and colleagues in Stem Cell Reports and Stem Cell Rev. The cGMP clinical-grade iPSC line – along with a parallel, identical, non-cGMP research grade iPSC line – is available to the research community through RUCDR Infinite Biologics at Rutgers University.

NIH Center for Regenerative Medicine and NIH Clinical Center join forces in an effort to harmonize informed consent for iPS cell-based research and therapies

The NIH Center for Regenerative Medicine has collaborated with the NIH Clinical Center Department of Bioethics on a manuscript that considers the challenges to obtaining informed consent to derive induced pluripotent stem (iPS) cells from donated tissue samples for research and therapeutic purposes. The manuscript provides concrete recommendations, along with a model consent form, in an effort to broadly harmonize informed consent, which currently varies considerably between tissue collection sites.

The promise of iPS cells in clinical therapies to replace damaged or diseased tissues, and as a resource for understanding a wide range of diseases and discovering candidate therapeutic drugs, is huge. However, to maximize their utility while safeguarding the donors that provide the starting material (e.g. skin) that the iPS cells are derived from, it is critical that informed consent is carefully considered now while the field is still nascent. This is particularly challenging when all the potential downstream uses of iPS cells are not yet know and can result in narrowly restricting the informed consent to a specific application at hand. Conversely, re-contacting donors/study participants indefinitely to re-consent to additional uses of the iPS cells, or to collect additional samples or information on their health, is not ideal either. This manuscript makes a cogent argument for a middle ground that balances the perspectives of a variety of stakeholders and arrives at a model consent form for the prospective collection of fresh specimens from which to derive iPS cells. Some important features include:

Research purposes are “open-ended” within the boundaries of all applicable laws and policies and may include transplanting cells or tissues made from iPS cells in to another patient to treat a disease

The iPS cells and participant’s medical information will be shared with other researchers to benefit medical research and society

Donors may be re-contacted for additional samples, medical information, or to consent to additional iPS cell uses not originally anticipated, but they do not need to oblige

A provision is included for donors to opt out of being re-contacted by researchers for any reason

Pediatric re-consent is incorporated to allow children to be informed upon reaching adulthood of the ability to review the previous consent and continue to participate in the study or not

Explicit language is included indicating that direct medical benefits for the donor are unlikely and no financial benefits will result from any commercial products developed from the iPS cells

Withdrawal at different stages of the research process is allowed. A request can be made to destroy any leftover original samples; however, any iPS cells already derived cannot be destroyed and any shared with other researchers cannot be retrieved, though the codes that link the sample to the donor can be removed

The implementation of a consistent approach to informed consent for iPS cell derivation and use across research/medical institutions in these early days as proposed in this manuscript could potentially be invaluable to providing stem cell researchers with crucial access to high-quality, thoroughly documented materials and resources.